Can a compressor with variable frequency operate at the first critical speed for an extended period of time?

The speed at which the rotor experiences severe vibration is a type of problem that has been well studied in rotor dynamics. In a rotating system, the centers of mass of various segments of the rotor cannot lie exactly on the axis of rotation. Therefore, as the rotor rotates, lateral disturbances occur, and at certain speeds these disturbances can cause severe vibrations in the system. The speed at which this happens is known as the critical speed. To ensure the proper operation of the system or to prevent it from being damaged due to vibration, the operating speed of the rotor in the rotating system should, as much as possible, be kept away from the critical speed; if this cannot be achieved, special vibration prevention measures must be taken. It is recommended to avoid using it within the critical speed range or at the boundaries as much as possible

Is it okay if it’s below this value? For example, 3000

This post was last edited by sdwfsgyykai on 2018-1-1 at 16:35; it is acceptable to operate below the critical speed

Original poster, your question: \"The critical speed at stage 1 is 3200. The compressor is currently operating at around 3200 all the time, and the vibration levels are within acceptable limits. I wonder if this is okay.\" ”~~~~Are you saying that the press is now running at 3200 rpm? Do you still plan to run it at this speed? ? If it’s the former case, then the first-order critical speed you mentioned is incorrect; therefore, don’t adjust it lightly. Wait until the machine is shut down, and under low-load conditions, use speed reduction to gradually determine the true critical speed ； If it is the latter, then the safe speed range is within ±400 rpm of the critical speed; that is, the adjustment range is: low range (0~2800), high range (3600~3900)~~~

No. This situation indicates that your machine’s critical speed is not 3200

The critical speed refers to the rotational speed at which vibrations occur; although the vibration level remains within acceptable limits, it is best to stay away from this range where vibrations can arise. It should be noted here that it remains to be confirmed whether the actual rotational speed in reality matches the critical speed specified in the design. Is this why the vibration value is low when the critical speed has been reached? Is the vibration low due to factors such as machining precision and reasonable design? ? Based on both the design specifications and actual measurement values, it is undeniable that this critical rotational speed, as per the principle behind it, is beneficial for the service life of the machinery.

If your vibration value is within the normal range, it means that the first critical speed of your machine is not 3200 rpm. If all current production parameters are normal, it is recommended not to change the existing speed settings lightly, as this could lead to unnecessary consequences.

I still don’t understand. Isn’t 3000 already above the level of 3200? Or is it not acceptable if it’s below 3200? Could you explain it again?

Mm-hmm, but now the anti-surge valve is set at almost half of its maximum range, which wastes electricity; the nameplate on the compressor indicates that the critical speed is 3200